Electric energy supply system for a ship, in particular a navy ship that can be operated with low IR signature

ABSTRACT

The invention relates to an electric energy supply system for a ship, in particular for a navy ship that can be operated with a low IR signature and that is configured as an &lt;&lt;all electric ship&gt;&gt; (AES). Said system comprises a direct current network (DC), supplied by fuel cells, as a ship electrical system and network for normal propulsion and an alternating current network (AC) comprising generators, in particular for generating energy for high-speed propulsion. According to the invention, the generators are motor-driven, e.g. by means of at least one gas turbine or one diesel motor, preferably supercharged and the AC and DC network are interconnected in such a way that electric energy can be exchanged between them, in particular that electric energy can be withdrawn from the DC network and transferred to the AC network to start the motor-driven propulsion.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/DE2003/002152 which has anInternational filing date of Jun. 27, 2003, which designated the UnitedStates of America and which claims priority on German Patent Applicationnumber DE 10231152.8 filed Jul. 10, 2002, the entire contents of whichis hereby incorporated herein by reference.

FIELD OF THE INVENTION

The invention generally relates to an electrical power supply system fora ship. In particular, it relates to one for a navy ship which can beoperated with a low IR signature, which is in the form of an “AllElectric Ship” (AES) having a DC power supply (DC), which is fed fromfuel cells, as the ship power supply system and as a power supply systemfor normal speed propulsion systems. The system further preferablyincludes an AC power supply system (AC) with generators, in particularfor power generation for high-speed propulsion systems. The generatorsare preferably motor-driven, for example by at least one gas turbine ora diesel engine, preferably a supercharged diesel engine.

BACKGROUND OF THE INVENTION

An electrical power supply system for water vessels, which correspondsto the power supply system described above, is known from German PatentApplication 101 02 741.9, Date of Filing: Jan. 22, 2001, which was notpublished prior to this.

SUMMARY OF THE INVENTION

An object of an embodiment of the invention is to specify a refinementof a corresponding electrical power supply system for a ship.Preferably, the refinement satisfies the particularly stringentrequirements for a navy ship with special high-speed propulsion systemsparticularly well. Additionally, it preferably allows improved or evenoptimum use of all the power generating devices which are provided onthe ship. In this case, the disclosure in German Patent Application 10102 741.9 is also intended to be included in the disclosure of thispatent application, and thus is incorporated herein by reference, in itsentirety and for all purposes.

The particular requirements for a power supply system for an AES aretaken into account in particular in that the AC and DC power supplysystems are connected to one another such that electrical power can beinterchanged between them, and in that electrical power is drawn fromthe DC power supply system and transferred to the AC power supply systemin particular for starting the engine drives. It is thus advantageouslypossible to achieve a starting process with a low IR signature forhigh-speed propulsion systems.

A refinement of an embodiment of the invention provides that the exhaustgases from the engine drives for the generators are introduced into areduced-pressure area at the base of the ship, with reduced pressure inthe reduced pressure area being produced during operation of thehigh-speed propulsion system by the water which is accelerated directlyor indirectly by the high-speed propulsion system. There is thusadvantageously no need for an exhaust gas compressor and/or units forproducing a reduced pressure in conjunction with the introduction of theexhaust gases into the water, even though the pressure here is up to onebar above the atmospheric pressure.

The introduction of the exhaust gases into a reduced-pressure area atthe base of the ship advantageously also results in the exhaust gasesbeing mixed particularly well with the water flowing around the base ofthe ship. Thus, since the exhaust gas bubbles which are formed do notrise until behind the stern of the ship where they merge into the sternvortices, this actually results in the ship being propelled in a mannerin which the exhaust gases cannot be detected. When using a gas turbineor a diesel engine for supplying power to electric motors for water jetsas high-speed propulsion systems, the exhaust gases are introduced intoa coaxial exhaust-gas nozzle segment of the water jets, with the waterjets being designed for operation at up to ten meters below thewaterline of the ship. Use is thus advantageously made of the ejectoreffect of the water jets, while at the same time using the spin of thewater jet. Overall, this results in a particularly good emissionbehavior of exhaust gases under the base of the ship.

When using diesel engines for the power supply for electric motors forpropeller propulsion systems as high-speed propulsion systems, theexhaust gases are advantageously introduced into an underwater nozzlesystem, for example into a Venturi tube system or an annular gas outletnozzle. Thus, the exhaust gases are introduced and distributed in thewater in a functionally similar manner to that with a water jet with acoaxial exhaust gas nozzle segment, even if there is a certain increasein the drag. Even when using diesel engines which supply power to thepropeller propulsion systems, an embodiment is thus possible whichprecludes infrared position-finding based on the exhaust gases.

A further refinement of an embodiment of the invention provides for abypass for the exhaust gases from the engine propulsion systems to anoutlet to be provided above the waterline, which may be used forstarting the engine propulsion systems. It is thus also advantageouslypossible to start the engine propulsion systems even whenreduced-pressure generation is not initially possible.

Within the scope of the embodiments of invention, provision is also madefor the fuel cells for the DC power supply system to be not only fuelcells whose power can be increased quickly, for example PEM cells, butalso fuel cells whose power can be increased more slowly, for exampleDMFC or SOFC cells or other cells which operate in the temperature rangeabove that of the PEM cells (approximately 80° C.). A basic load supplyand a peak load supply can thus also advantageously be achieved for theDC power supply system, with the combination of different fuel cells andtypes allowing a fuel cell power supply which is particularlycost-effective and whose efficiency is optimized. A power supply such asthis can advantageously very well satisfy both the dynamic and thesteady-state requirements for the power supply in a navy ship.

One refinement of an embodiment of the invention advantageously providesin this case for the various fuel cells to be operated in the media(gas/water) and heat combination and to feed electrical power into theDC power supply system jointly. If required, they can also operatejointly with one or more reformers. This may result in a veryadvantageous high efficiency with little heat being generated, in whichcase the remaining heat may also still be used, for example, for coolingpurposes in an absorber cooling system.

The starting processes for the high-speed propulsion units areadvantageously drawn from PEM cells, while the basis ship power supplyis drawn from fuel cells with a higher operating temperature. Thestarting processes for the high-speed propulsion units require a largeamount of energy, since the units must be accelerated by means ofexternal energy up to the minimum operating rotation speed, that is tosay the PEM cells must be able to supply a correspondingly large amountof power, and must be designed for this purpose.

For navy ships, it is particularly advantageous for fuel cells with adifferent dynamic response to be combined to form technicallyinteracting units which are distributed in different ship areas. Thisresults in a high degree of insensitivity to hits, since, even if severedamage occurs in individual ship areas, the power generation cancontinue in an optimized manner in the other ship areas.

A refinement of an embodiment of the invention advantageously providesfor the fuel cells to have a DC switching system with a monitoring andcontrol system, and with the power generation units for the high-speedpropulsion systems likewise having an AC switching system with amonitoring and control system. This allows energy management matched tothe requirement to be provided for both power supply systems. Both powersupply systems can be controlled, regulated and monitored completelyindependently of one another. Even if one power supply system fails, theother power supply system remains fully serviceable, without any change.

Furthermore, one refinement of an embodiment of the invention providesfor the AC monitoring and control system to be connected to pressuresensors, in particular to reduced-pressure sensors in the exhaust gasoutlet reduced-pressure areas, and to pressure sensors in exhaust gaslines, and to be connected to valve and flap control devices and,possibly, to position sensors for valves and flaps. This thereforeprovides a basis for automation of the starting and accelerationprocesses of the individual power generators. With the aid of this, amonitoring and control system can be operated with exhaust gas controlswitching logic (automation system). It may have the conventionalelectronic automation components, such as actuating rate ramps,interlocks, etc. and may be operated particularly advantageously on thebasis of Siemens SIMATIC S7 appliances and/or other devices/systems forhandling automation processes remotely.

Appliances such as these are also available as high-availability SPSappliances which operate intrinsically in a redundant manner and whichcan advantageously carry out the entire automation process. In thenormal form or in the high-availability form, they contribute in aparticular manner to the reliability of the automation processes.Undesirable circuit states, which damage the propulsion system, can thusreliably be avoided; e.g. oil pressure in the bearings, fuel pressureand temperature, starting and ignition process etc., that is to say thestarting conditions, can thus be maintained reliably.

If required, provision is made within the scope of the invention for theexhaust gas supply system to have a compressed-air feed subsystem, inparticular for blowing out the reduced-pressure areas and/or foracceleration of the flow of the exhaust gases during the startingprocess. An aid is thus advantageously available for improving andaccelerating the starting processes. The reliability of the startingprocess for the propulsion systems which are required to reach highspeeds can thus be improved considerably. If the high-speed propulsionsystems are driven by compressed-air-started diesel generator sets,their compressed-air reservoir can also be used.

Provision is also made within the scope of the invention for the powersupply system to have a control system which operates at a higher levelthan the AC and DC switching systems with their respective monitoringand control systems, which higher-level control system matches the powergeneration and the power consumption of all the power generators andloads to one another, in particular with respect to the differentdynamic responses of the power generators and loads. This makes itpossible to avoid, in a battle for example, less power than is requiredbeing available for components of the navy ship which are required forsurvival. In this case, for example, in the relevant situation,unimportant loads, such as galleys, air-conditioning systems etc., aredisconnected from the ship power supply system and all of the availablepower is concentrated on the equipment that is required for survival.

A refinement of an embodiment of the invention in this case provides forthe AC and DC switching systems to be designed such that, when there isa high demand for power in the DC power supply system, for example whenusing high-energy weapons, it is possible to feed a maximum amount ofpower from the AC power supply system to the DC power supply system.Furthermore, in this context, provision is also made for the DC powersupply system to have high-dynamic response energy stores, for examplerechargeable battery banks or flywheel energy stores. These devices havethe common feature that their operation can be used to cope with suddendemands for power to be made available in the ship power supply system.The AC and DC power supply systems are thus designed such thatelectrical power can be used from both power supply systems in order tomeet the requirement.

The invention may be described in general form and by way of example asfollows:

In order to minimize the IR signature of surface navy ships, the exhaustgases from diesel engines and/or gas turbines should be dissipated viacoaxial exhaust gas nozzle segments or the like in conjunction with oneor more water jets by making use of the pressure drop region (reducedpressure=suction) below the waterline as a water/exhaust gas mixture. Anelectrical circuit arrangement allows the water jets which are driven byelectric propulsion motors to be started before the starting of thediesel engines and/or gas turbines which drive the electricitygenerators for generation of the electrical power for the water jets.

The power for the water jets is increased until an appropriatereduced-pressure region is formed in coaxial exhaust gas nozzlesegments, or the like. Only then are the diesel engines and/or gasturbines started, with the exhaust gas supply being connected such thatthe exhaust gases are passed directly to the coaxial exhaust gas nozzlesegment. Once the diesel engines and/or gas turbines have beenaccelerated, the generators take over the supply of the electrical powerfor the water jet motors. The power of the water jets can now beincreased to their maximum possible power level. The same applies tohigh-speed propeller propulsion systems which may be used instead of thewater jets, with the coaxial exhaust gas nozzle segments being replacedby axial exhaust gas nozzle segments.

The electrical circuit arrangement is designed as follows:

One to n fuel cell systems (BZA), by way of example four BZAs in FIG. 1,supply the propulsion and ship power supply system with electrical powerwithout any emissions. The BZAs produce their electrical power in theform of a DC voltage. The BZAs normally supply the cruise speedpropulsion system, in the drawings by way of example one or moreelectrical steering propeller propulsion systems, the weapon systems andthe ship power supply system with electrical power. One or more ACgenerators which are driven by diesel engines and/or gas turbines supplypower to the electrical propulsion motors for the additional propulsionsystems, in the figures water jets for the ship.

One or more static DC/AC converters is or are arranged between at leastone of the DC distribution busbars and at least one AC distributionbusbar. The electrical power can flow via these converters from the DCdistribution busbar to the AC distribution busbar, and vice versa. Forexample, in order to minimize IR emissions, the water jets can bestarted with electrical power from the BZAs. Furthermore, in anemergency, for example in the event of failure of the BZAs, the DC powersupply system can be supplied with electrical power from the ACgenerators, which are driven by diesel engines and/or gas turbines,although, in this case, this may be without the IR signature beingminimized.

When the operating mode of the ship is changed from water jet propulsionsystems to cruise-speed propulsion systems, the reverse procedure isadopted for operation with a minimized IR signature. The power of thewater jets is reduced to such an extent that there is still sufficientreduced pressure for exhaust suction/dissipation of the exhaust gasesfrom the diesel engines and/or gas turbines in the coaxial exhaust gasnozzle segment. The DC/AC converters are activated, and the electricalpower supply is transferred from the BZAs to the water jet or jets. Thepower of the AC generators is reduced to zero, and they are disconnectedfrom the AC distribution busbar. The diesel engines and/or gas turbinesare then slowed down and switched off. The power of the water jets cannow likewise be reduced to zero, and they can be switched off.

The IR signature of surface navy ships is thus also minimized in thephases in which the high-speed propulsion systems are being switched onand off. It is thus not possible to use IR sensors to detect theposition of a ship that is equipped in the manner according to anembodiment of the invention from relatively long range either at cruisespeed with a fuel cell propulsion system or in the transitional phasesto very high speed or from very high speed back down to cruise speed, orwhen traveling at very high speed.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, features and details of the invention will becomeevident from the description of illustrated exemplary embodiments givenhereinbelow and the accompanying drawings, which are given by way ofillustration only and thus are not limitative of the present invention,wherein:

FIG. 1 shows a propulsion system with a low IR signature for a navysurface ship, in outline form, with system detail elements, and

FIG. 2 shows the principle of the power supply system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1, 1, 2, 3 and 4 each denote a fuel cell unit which mayoptionally comprise a PEM cell block or a combination of a PEM cellblock with another fuel cell with a higher operating temperature. Afunctional combination of the two different fuel cells is produced in acombination such as this. The electrical power which is produced by thefuel cell systems 1, 2, 3 and 4 is passed to electrical DC switchingsystems 5, 6 which, if required, may also be combined, and in which casemore than two DC switching systems (electrical mechanisms) may also bearranged depending on the safety, reliability and redundancyrequirements, and passed from here via DC/AC converters 7, 8 to theelectrical switching system 9, an AC switching system.

Both the generator 10 and the electric motor 15 for the water jet 17 areswitched by the electrical switching system 9. The generator 10 isconnected to the gas turbine 11, whose exhaust gases are optionallypassed to the atmosphere—switchably via the switching device 12, throughthe exhaust gas line 13—in special cases—or normally via the exhaust gasline 14 to the coaxial exhaust gas nozzle segment 18 of the water jet17.

A propulsion shaft 16 is arranged between the electric motor 15 and thewater jet 17. The water jet inlet into the water jet 17 is indicated bythe arrows 19 and, as indicated, the water leaves the water jet 17 inthe water exhaust gas cone 20. The lower edge of the ship is annotated21. The water jet is located considerably below the waterline, generallybetween 5 and 12 m. The water pressure to be overcome corresponds tothis.

In FIGS. 2, 22 and 23 each denote a DC busbar, and these busbars extendbetween the fuel cell units 26, 27, 28 and 29. The power from the DCbusbars 22, 23 is passed to the AC busbar 30 via connecting lines 24, 25with converters 40, 41. A steering propeller 33, which is shown by wayof example, is connected to the DC busbar 23 and is supplied with powervia an inverter 31, and another steering propeller 36, which is shown byway of example, is likewise supplied with power via the inverter 32.Normal propeller propulsion systems may, of course, also be used insteadof the steering propellers.

The AC busbar 30 is supplied with power by the generators 34, 36, whichare driven by gas turbines 35, 38. The water jet pairs 34, 35 aresupplied with power from the AC busbar 30. The other switching devices,which are illustrated only in an indicated form, are located between theindividual busbars, which are shown by way of example in FIG. 2, andtheir parts. A bow thruster 42 is also connected to the DC busbar 22and, because its power level is low and it is used only rarely, it maybe fed from the DC power supply system. The DC busbars 22, 23 areconnected to one another by means of a transfer line 37 so that,overall, this results in a complete ship power supply system, althoughFIG. 2 illustrates only the major components.

Exemplary embodiments being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the present invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

1. An electrical power supply system for a ship, comprising: a DC powersupply system; and an AC power supply system with generators, thegenerators being motor-driven, wherein the AC and DC power supplysystems are connected to one another such that electrical power isinterchangable between them, and wherein electrical power is drawn fromthe DC power supply system and transferred to the AC power supplysystem, wherein the system includes a control system which operates at ahigher level than the AC and DC switching systems with their respectivemonitoring and control system, which higher-level control system matchesthe power generation and the power consumption of all the powergenerators and loads to one another.
 2. The electrical power supplysystem as claimed in claim 1, wherein exhaust gases from engine drivesfor the generators are introduced into a reduced-pressure area at thebase of the ship, with reduced pressure in the reduced pressure areabeing produced during operation of a high-speed propulsion system,including the AC power supply system, by the water accelerated at leastone of directly and indirectly by the high-speed propulsion system. 3.The electrical power supply system as claimed in claim 2, wherein theexhaust gases, when using at least one of a gas turbine and a dieselengine as the engine drives, are introduced into coaxial exhaust-gasnozzle segments of water jets for supplying power to electric motors forwater jets as the high-speed propulsion systems, with the water jetsbeing designed to operate at up to ten meters below the waterline of theship.
 4. The electrical power supply system as claimed in claim 2,wherein the exhaust gases, when using diesel engines for the powersupply for electric motors for propeller propulsion systems ashigh-speed propulsion systems, are introduced into an underwater nozzlesystem.
 5. The electrical power supply system as claimed in claim 2,wherein a bypass is provided for the exhaust gases from the enginedrives to an outlet above the waterline, which may be used for startingthe engine drives.
 6. The electrical power supply system as claimed inclaim 2, wherein the exhaust gases, when using diesel engines for thepower supply for electric motors for propeller propulsion systems ashigh-speed propulsion systems, are introduced into at least one of aVenturi tube system and an annular gas outlet nozzle.
 7. The electricalpower supply system as claimed in claim 3, wherein a bypass is providedfor the exhaust gases from the engine drives to an outlet above thewaterline, which may be used for starting the engine drives.
 8. Theelectrical power supply system as claimed in claim 4, wherein a bypassis provided for the exhaust gases from the engine drives to an outletabove the waterline, which may be used for starting the engine drives.9. The electrical power supply system as claimed in claim 1, wherein theDC power supply system is fed from fuel cells that have a DC switchingsystem with a monitoring and control system.
 10. The electrical powersupply system as claimed in claim 9, wherein the system is connected toan exhaust gas supply system, which allows switching of the exhaust gassupply.
 11. The electrical power supply system as claimed in claim 10,wherein the exhaust gas supply system includes a compressed-air feedsubsystem.
 12. The electrical power supply system as claimed in claim11, wherein the compressed-air feed subsystem one of blows out thereduced-pressure areas and accelerates the flow of the exhaust gasesduring a starting process.
 13. The electrical power supply system asclaimed in claim 1, wherein power generation units for the high-speedpropulsion systems have an AC switching system with a monitoring andcontrol system.
 14. The electrical power supply system as claimed inclaim 13, wherein the system is connected to an exhaust gas supplysystem, which allows switching of the exhaust gas supply.
 15. Theelectrical power supply system as claimed in claim 1, wherein an ACmonitoring and control system is connected to pressure sensors and topressure sensors in exhaust gas lines.
 16. The electrical power supplysystem as claimed in claim 1, wherein an AC monitoring and controlsystem is connected to valve and flap control devices.
 17. Theelectrical power supply system as claimed in claim 1, wherein an ACmonitoring and control system has an exhaust gas supply switching logic,and wherein an automation system based on the same technology isprovided for the propulsion systems.
 18. The electrical power supplysystem as claimed in claim 1, wherein the AC and DC switching systemsare designed such that a maximum amount of power is feedable from the ACpower supply system to the DC power supply system when the power demandin the DC power supply system is high.
 19. The electrical power supplysystem as claimed in claim 1, wherein the AC and DC systems are designedsuch that the DC power supply system can be supplied with powercontinuously from the AC power supply system when fuel cells for powergeneration fail at least partially.
 20. The electrical power supplysystem as claimed in claim 1, wherein the DC power supply system hashigh-dynamic-response energy stores.
 21. The electrical power supplysystem as claimed in claim 1, wherein the system is for a navy shipoperatable with a low IR signature, which is in the form of an “AllElectric Ship” (AES).
 22. The electrical power supply system as claimedin claim 1, wherein a DC power supply, fed from fuel cells, is includedin the DC power supply system and is a power supply system for normalspeed propulsion systems.
 23. The electrical power supply system asclaimed in claim 1, wherein the AC power supply system includesgenerators for supplying power for high-speed propulsion systems. 24.The electrical power supply system as claimed in claim 23, wherein thegenerators are motor-driven by at least one of a gas turbine and adiesel engine.
 25. The electrical power supply system as claimed inclaim 1, wherein electrical power is drawn from the DC power supplysystem and transferred to the AC power supply system for starting theengine drives.
 26. The electrical power supply system as claimed inclaim 1, wherein fuel cells for the DC power supply system are both fuelcells whose power is quickly controllable and fuel cells whose power isslowly increasable.
 27. The electrical power supply system as claimed inclaim 26, wherein fuel cells are at least one of DMFC cells, SOFC cellsand other cells which operate in the temperature range above the PEMcells.
 28. The electrical power supply system as claimed in claim 26,wherein fuel cells are at least one of DMFC cells, SOFC cells and othercells which operate in the temperature range of approximately 80 degreesC.
 29. The electrical power supply system as claimed in claim 26,wherein different fuel cells operate in media and heat combination, andjointly feed electrical power into the DC power supply system.
 30. Theelectrical power supply system as claimed in claim 26, wherein acapacity of the fuel cells whose power is quickly controllable isdesigned such that at least the starting processes of high-speedpropulsion systems can be carried out.
 31. The electrical power supplysystem as claimed in claim 26, wherein fuel cells with a differentdynamic response are combined to form technically interacting units, andare distributed between different ship areas.
 32. The electrical powersupply system as claimed in claim 1, wherein an AC monitoring andcontrol system is connected to reduced-pressure sensors in exhaust gasoutlet reduced-pressure areas, and to pressure sensors in exhaust gaslines.
 33. The electrical power supply system as claimed in claim 1,wherein an AC monitoring and control system is connected to valve andflap control devices and to pressure sensors.
 34. The electrical powersupply system as claimed in claim 1, wherein an AC monitoring andcontrol system includes an exhaust gas supply switching logic withactuating rate ramps and interlocks and wherein an automation systembased on the same technology is provided for the propulsion systems. 35.The electrical power supply system as claimed in claim 1, wherein thesystem includes a control system which operates at a higher level thanthe AC and DC switching systems with their respective monitoring andcontrol system, which higher-level control system matches the powergeneration and the power consumption of all the power generators andloads to one another with respect to the different dynamic responses ofthe power generators and loads.
 36. The electrical power supply systemas claimed in claim 1, wherein the AC and DC switching systems aredesigned such that a maximum amount of power is feedable from the ACpower supply system to the DC power supply system when using high-energyweapons.
 37. The electrical power supply system as claimed in claim 18,wherein the AC and DC systems are designed such that the DC power supplysystem can be supplied with power continuously from the AC power supplysystem when fuel cells for power generation fail at least partially. 38.The electrical power supply system as claimed in claim 1, wherein the DCpower supply system has at least one of rechargeable battery banks andflywheel energy stores.
 39. The electrical power supply system asclaimed in claim 22, wherein the AC power supply system includesgenerators for supplying power for high-speed propulsion systems.
 40. Anelectrical power supply system, comprising: an AC power supply system;and a DC power supply system, wherein fuel cells for the DC power supplysystem are both fuel cells whose power is quickly controllable and fuelcells whose power is slowly increasable; wherein the AC and the DC powersupply systems are connected to one another such that electrical poweris interchangable between them, wherein fuel cells with a differentdynamic response are combined to form technically interacting units, andare distributed between different ship areas.
 41. The electrical powersupply system as claimed in claim 40, wherein different fuel cellsoperate in media and heat combination, and jointly feed electrical powerinto the DC power supply system.
 42. The electrical power supply systemas claimed in claim 40, wherein a capacity of the fuel cells whose poweris quickly controllable is designed such that at least the startingprocesses of high-speed propulsion systems can be carried out.
 43. Theelectrical power supply system as claimed in claim 40, wherein fuelcells are at least one of DMFC cells, SOFC cells and other cells whichoperate in the temperature range above the PEM cells.
 44. The electricalpower supply system as claimed in claim 40, wherein fuel cells are atleast one of DMFC cells, SOFC cells and other cells which operate in thetemperature range of approximately 80 degrees C.
 45. The electricalpower supply system as claimed in claim 40, wherein an AC monitoring andcontrol system includes an exhaust gas supply switching logic withactuating rate ramps and interlocks and wherein an automation systembased on the same technology is provided for the propulsion systems.